1. Field of Invention
The invention relates generally to methods and apparatus for controlling robotic manipulators. More particularly, the invention relates to methods and apparatus for providing a user who is controlling a remote robotic manipulator with sensations relating to the environment in which the robotic manipulator is operating.
2. Description of Relevant Art
Robotic manipulators are often used to enable a user at one site to perform operations at a second site, e.g., a remote site. The use of robotic manipulators at remote sites allows operations to be performed at the remote site without exposing a person to the environment at the remote site. By way of example, a robotic manipulator may be used to retrieve objects from a hazardous environment, thereby preventing a person from having to enter the hazardous environment.
Robotic manipulators may generally be controlled using a variety of different mechanisms. One mechanism which is often used to control at least some movements of a robotic manipulator is a command glove system. Sensors associated with a command glove system are arranged to transmit human hand motions to a robotic manipulator and to receive signals from the robotic manipulator. Signals received from the robotic manipulator are often used to control human hand motions in response to forces encountered by the robotic manipulator. Some command gloves attempt to control substantially every degree of freedom in the human hand. Command gloves which are intended to control every degree of freedom in a hand generally require a significant number of electronic and mechanical components. Many command gloves, especially those which attempt to control every degree of freedom in a human hand, end to restrict the hand movement of a user who is wearing the command glove, since the volume of components required typically causes the command glove to be heavy and bulky, or otherwise difficult to manipulate. Further, a volume of electrical components often requires a significant amount of power usage.
In response to the motions and forces applied by a human hand, i.e., a hand using a command glove, an associated robotic manipulator moves and applies force to its surroundings. When the robotic manipulator applies force to its surroundings, sensors located on, or associated with, the robotic manipulator transmit force information from the robotic manipulator back to the glove, as mentioned above. Actuators located on the glove may then transfer the force information back to the human.
Actuators which transfer force information to a human generally do not simulate the actual sensations experienced by a robotic manipulator back to the human. By way of example, actuators on gloves are not arranged to simulate the sensations a human might be likely to feel when the human grasps a solid object. Instead, the glove, e.g., the TeleTact glove developed at the Advanced Robotics Research Center in the United Kingdom, may expand pneumatic bladders on the glove in response to increased forces "applied" to the robotic manipulator when the robotic manipulator grasps a solid object. However, when a human, or robotic, hand grasps a solid object, the object does not actually apply forces to the hand. Instead, the object resists the forces applied by the hand. Therefore, in some cases, the use of actuators to apply forces to a hand may not be an accurate simulation of sensations experienced by the robotic manipulator when the robotic manipulator grasps an object.
Some command gloves allow a user to experience vibrations which are present in the environment of a robotic manipulator. Such command gloves generally include vibration actuators which may be activated in response to signals transmitted from the robotic manipulator. By enabling the user to experience vibrations and forces felt by the robotic manipulator, the user is presented with a better sense of what the environment around the robotic manipulator is like.
Although vibration actuators are included in some command gloves in addition to force actuators, command gloves generally do not provide a user with force feedback and a sense of the thermal environment experienced by the robotic manipulator. In other words, information relating to the thermal environment of the robotic manipulator generally is not experienced by a user. Providing a user with thermal sensations, e.g., a sense of heat, experienced by the robotic manipulator would enable the user to monitor the thermal environment of the robotic manipulator and, hence, modify the actions of the robotic manipulator as necessary.
Therefore, what is desired is a method and an apparatus for efficiently and accurately providing a sense of the environment which is being experienced by a robotic manipulator to a user that is commanding the robotic manipulator. Specifically, what is desired is a relatively lightweight command glove which consumes a minimum of external power, and accurately provides a user with a haptic sense of the environment in which a robotic manipulator is operating.